Many geothermal and geopressured brines contain high concentrations of minerals which are potentially valuable. Frequently, a portion of these minerals precipitate in process equipment in a geothermal power plant as scale. Such scale must periodically be removed to allow for continued operation of the power plant. Dismantling and cleaning of process equipment is a major operating and maintenance expense for the owner of a power plant which handles brines of this type.
In U.S. Pat. No. 4,370,858, there has been disclosed an apparatus and a method for energy production and mineral recovery. The apparatus disclosed in this patent includes one or more flash-crystallizer-separator units which are used to receive brine from a geothermal production well to cause three-phase fluidization of the brine to separate it into gaseous, liquid and solid fractions. For instance, the gaseous fraction is used for performing useful work, such as driving a turbine. The liquid and solid fractions are used to support crystal growth and thereby recover mineral values from the brine. Use of an improved flash-crystallizer-separator with geothermal and geopressured brine was described in the above patent.
Improvements in mineral recovery are desirable to increase the yield of minerals, especially heavy metals such as lead, silver and zinc, from brines of the type described. A need continues to exist for such improvements, and the present invention describes an apparatus and method for promoting the additional formation of solids of commercial value which are then separated from the brine. The invention also provides a means and method for preventing scale formation in production wells.
Additional disclosures relating to the handling of geothermal and geopressured brines include U.S. Pat. Nos. 4,202,864, 4,123,506, 4,242,305 and 4,374,106.